1. Field of the Invention
The present invention relates to a method and apparatus for removing nitrogen oxide from gas (exhaust gas) discharged, for example, in the steps of plating, washing with acids, dissolution, etc.
2. Prior Art
Heretofore, it is known that gas (exhaust gas) is discharged, for example, in the steps of plating, washing with acids, dissolution, etc., for surface treatment of metals, etc. To remove nitrogen oxide from such exhaust gas, known is a method of spraying a mist of a liquid containing aqueous hydrogen peroxide and sodium hydroxide over said exhaust gas to make said liquid react with the nitrogen oxide in the exhaust gas followed, thereby removing the nitrogen oxide from the exhaust gas. Apparatus to which this method is applied have been put to practical use.
However, this conventional method, as using such a liquid containing aqueous hydrogen peroxide and sodium hydroxide, had a problem in that special care shall be taken in handling the sodium hydroxide which is a strong alkali. In addition, since such a mist comprising aqueous hydrogen peroxide and sodium hydroxide is brought into contact with exhaust gas in said conventional method, the method had still another problem in that the contact efficiency between the mist and exhaust gas is poor and therefore the efficiency of removing nitrogen oxide from the gas is poor.